Officer Dennis came to Hawaii via the U.S. Army from Hageman, Idaho in 1937 before joining the Honolulu Police Department in 1941.

On May 2, 1942, Officer Dennis was citing a motorist for a black-out violation when he observed a vehicle speed past him. Officer Dennis ordered the driver of the vehicle he was engaged with to drive after the vehicle speeding by. While standing on the running board of the moving vehicle as it attempted to catch up to the speeding vehicle, they were quickly approaching an unseen truck-trailer up ahead. The driver, at the last minute, observed the truck-trailer and swerved left to avoid a collision. It was at this time Officer Dennis struck the rear of the truck as the maneuver was made to avoid the moving vehicle. The truck-trailer had no tail lights and was unseen until just before the collision.